i had the same problem i disabled Motorola Assist now the phone is very loud best speaker phone
and calls are great.THIS IS WHY I KEEP THIS PHONE CALL QUALITY ROCKS
by now every one must have figured this out

I'm having the same exact problem as Sue. I noticed the phone stopped working within the past day or so. If I'm on regular handset mode I can't hear anything and the receiving caller cannot hear me. If I switch to speaker-mode I can hear the receiver and the receiver can hear me. I'm not quite sure what's going on but I've disabled Motorola Assist, removed any recent apps I installed and especially those dealing with voice recognition, etc, and also wiped the partition and davlik caches. Does anyone know why this is happening?

The only thing I can think of is that I quickly rinsed the phone off (which I've done several times before and was comfortable doing per the many "moto g waterproof" tests I've seen) after getting home and noticed that after that is when I think things started happening. So I'm thinking maybe the phone got water damaged? But why would speakerphone still work?

I also noticed that I can't play or hear any audio from the phone (via Youtube or Google Play, etc). If I plug in earbuds or headphones though, it works. It's really weird that voice calls via speakerphone still work though. Unfortunately, this is a Boost mobile pre-owned device that I got that only has a 14-day satisfaction guarantee (and it's been well over 14 days). Plus, I flashed it to work on Verizon/PagePlus...

Turns out, I'm pretty sure, it was from doing a quick-rinse. The mic and or speaker components may have gotten slightly wet and probably shorted on calls and what not. I think the volume overall may have gotten affected too but at this point, after some time everything seems to work again (after everything inside that got wet dried out, I'm guessing). Anyway, lesson learned. I definitely won't be rinsing the phone off anymore haha. I really need to find a fully waterproof phone

If you hear a buzzing sound on the earpiece during a call, you should first test it to see whether there is an issue with the earpiece itself. To do so, you have to first make sure that USB Debugging is enabled, by going into Settings – Developer Options – USB Debugging. Then dial ##2486## in the dialer, and that should open up the test menu. Select the first bar, then select Audio, click on Earpiece, and choose Buzz Test. Hold the phone to your ear, and you will hear a harmonic sound that starts on a lower frequency and goes to an higher frequency, that will repeat. If you don’t hear any distortion in this loop that is played, then there are no issues with your earpiece at all.

If you do have a faulty earpiece, the only solution is to go pick up a replacement device. If there’s nothing wrong with the device, then go into Settings – Sound – Audio Effects, and turn it off. If that doesn’t work, in the Audio effects section, go into Speaker, and turn the equalizer off. That should do the trick, but if it doesn’t you may need to flash a lower firmware version. You can find out more about that process here.

If you’re facing any other issues with audio quality, go into Audio Effects, and you can change the equalizer settings in the Wired Stereo and Speaker sections separately.